TPS23753AEVM-004: TPS23753A

govindveera

Hi,

I have a mysterious problem. I am using TPS23753AEVM-004 reference design for my PoE based power supply. I have both options. I will use wall adaptor or PoE PD as power supply input. The power section is working well with PoE but its not working with wall adaptor. What will be the problem?

over 5 years ago

0 Thomas Lewis over 5 years ago

TI__Expert 5615 points

Greetings govindveera.

As it is the weekend, our Application Engineer coverage is minimal today. We can provide better detail tomorrow but it might help them solve this issue more quickly if you can provide details on the AC wall adapter you are attempting to utilize.

What is it's operating voltage - 12V?

Thank you for considering PoE solutions from Texas Instruments,

0 govindveera over 5 years ago in reply to Thomas Lewis

Intellectual 395 points

Hi Thomas,
That is 24V/2A adaptor. The voltage in APD pin is around 2V. I am using the same adaptor for other boards, all boards are working except two boards.

0 Thomas Amlee over 5 years ago in reply to govindveera

TI__Genius 9230 points

Hi Govindeera,

On your TPS23753AEVM-004, are you attaching the 24V/2A adapter to the J4 input (Vdd-Vss) or the J6 input (Vdd-RTN)?

The J4 input is 36V-57V, while the J6 input is 12V-54V.

Regards,
Tom A.

0 govindveera over 5 years ago in reply to Thomas Amlee

Intellectual 395 points

POE POWER SUPPLY.pdfYes. I attached my schematic with this. Please refer. For current loop CL11, I am just using a jumber.

0 Thomas Amlee over 5 years ago in reply to govindveera

TI__Genius 9230 points

Hi Govindeera,

The D114 diode should be placed after the resistor divider (R126 & R127). The diode drop is lowering the voltage present at the APD pin, so it is not meeting 1.5V APD rising threshold. If you are still having trouble hitting this threshold, try increasing the R127 resistor to 56k.

Thanks,
Tom A.

0 Thomas Lewis over 5 years ago in reply to Thomas Amlee

TI__Expert 5615 points

Govindeera,

We believe this to have resolved your issue. Please let us know if needing additional assistance or click on the 'Resolved' button if this thread is closed in your mind.

Thank you for your interest in PoE products from Texas Instruments,

0 govindveera over 5 years ago in reply to Thomas Lewis

Intellectual 395 points

Thank you Thomas.

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TPS23753AEVM-004: TPS23753A